To facilitate the design and manufacture of wireless communication systems, a group of radio system experts codify the characteristics of a system into a standard. These characteristics typically include a specific operating radio frequencies, output power requirements, receiver sensitivity requirements, data rate requirements, communication protocols, security protocols, modulation types and spurious radio frequency emission requirements to name a few. Many standards exist for different wireless communication systems. These standards can be public domain or proprietary. Public standards include the well-known Global System for Mobile communication (GSM), Bluetooth™ and 802.11 standards.
Conventional practice is to design and optimize a radio transceiver targeted to a particular standard. For example, a radio transceiver to be used in a device that operates using the Bluetooth™ communication protocol is sized and customized to the Bluetooth™ protocol. Generally, the same can be said for radio transceivers designed for use in devices that operate using the IEEE 802.11 communication protocol.
However, there are many applications which need to operate in multiple communication protocol technologies, or operate multiple instances of the same communication protocol technology. In many of these applications, the information arrives on one communication protocol and is sent out on another communication protocol. For example, a GSM cellular telephone device may operate with a Bluetooth™ headset. The voice data is sent wireless from the headset to the cellular telephone on one communication standard, Bluetooth™, and then from the cellular telephone wirelessly to the cellular base station on another standard, GSM. Likewise, voice data might be received by a cellular handset from a cellular base station using the GSM standard and then retransmitted to the headset using Bluetooth™.
There is also a trend to reduce cost in wireless transceivers. On way to do so is to use a multi-mode radio that is capable of transmitting and receiving multiple standards rather than using one radio for each standard. While using a multi-mode radio lowers the cost of the system, the disadvantage is that typically only one standard can be transmitted or received at a time. In addition, most integrated circuit radios can not receive and transmit at the same time.
A multi-mode wireless bridge communicates to a plurality of other wireless systems, each of which may adhere to a different radio communication standard. The communication between two wireless devices is known as a link. A multi-mode wireless device can form links with other single-mode or multi-mode devices. Each link may adhere to a different communication standard. The bridge receives information on one link using a particular radio communication protocol, demodulates the signal to information bits, and then re-modulates and transmits on a different link using a different communication protocol.
As shown in FIG. 1, a single-mode wireless transceiver 11 uses a first wireless communication standard to send information over a wireless link 12 to the multi-mode wireless transceiver 13. The multi-mode wireless transceiver 13 receives the signals, converts them to a second radio communication standard and transmits them over a wireless link 14 to a second single-mode wireless transceiver 15. This second single-mode wireless transceiver, in general, adheres to a second radio communication standard different than the first radio communication standard.
In this way, the multi-mode wireless transceiver 13 has acted as a wireless bridge between the two single-mode wireless transceivers 11, 15. As an example, the radio communication standard described in this example could be Bluetooth™, HomeRF, 802.1a or GSM. In general, a multi-mode wireless system can communicate with many different devices using different radio communication standards and thus, acts as a bridge between many standards. A multi-mode wireless communication bridge is typically-made up of multiple transceivers each designed for a specific standard. For these transceivers to coexist, they are isolated from one another through the use of electronic shielding and filtering.
FIG. 2 shows a traditional multi-mode wireless system supporting three standards. The first standard implemented in a multi-mode wireless communication system requires its own antenna 21, radio 22, and baseband sub-system 23 each tailored for the first standard. An additional standard in the multi-mode system requires another antenna 24, radio 25 and baseband sub-system 26. The third standard requires its own antenna 27, radio 28 and baseband sub-system 29. Each baseband sub-system can communicate to each other using a shared communication bus or shared memory 20. When a baseband system demodulates the incoming signal into information bits, it can send the information bits to a different baseband system for retransmission using a different standard. A plurality of standards can be bridged this way in a multi-mode system.
Consequently, it is desirable to provide a multi-mode radio transceiver system that can bridge between multi-standards using only a single transceiver.